The present invention generally relates to apparatus for dispensing microliter amounts of medicament and is more particularly directed to apparatus for instilling a medicament into an eye.
A great number of devices have been developed for instilling medicament to an eye. Well known eye drop containers conventionally include a squeezable container and a nozzle for releasing drops of medicament into the eye by compression of the container. Obviously, this apparatus affords no practical method of dispensing a measured, or metered, dose of medicament inasmuch as the liquid dispensed from the nozzle is dependent upon the amount of compression of the container. Thus, there is no way of accurately controlling the volume of each dose of medicament released into the eye and, further, the smallest drop obtainable is the result of the combined effective gravity and surface tension.
When preservative-free medicaments are utilized, simple eye drop dispensers are not practical because there are no means for preventing the tip from being contaminated due to its exposure to air. Such tip contamination ultimately spreads to the medicament in the container.
In an attempt to overcome these problems, apparatus has been developed for applying a medicament to an eye which includes a nozzle having a seam which is normally in a closed position for preventing the passage of medicament through the nozzle, and which opens in response to a flow of medicament of sufficient pressure to enable opening of the seam in order to permit the passage of medicament through the nozzle for release into the eye, see U.S. Pat. No. 5,685,869.
While this nozzle is suitable, there is difficulty in coupling the nozzle with a suitable reservoir of medicament in order to create a working, producible device for multiple dose delivery of a preservative-free product of sufficient dose accuracy for consumer benefit and regulatory body registration over an extended period of time of up to six months or more.
Operation of prior art devices such as set for the in the hereinabove referenced U.S. Patent typically cause a small negative pressure or vacuum within the medicament container during operation. When a collapsible container is utilized to accommodate shrinking of volume of the medicament reservoir, the materials of construction do not satisfactorily inhibit the permeating of air through the container walls to provide a desired long term use in storage of the device without compromise of the stored medicament.
U.S. patent application Ser. No. 09/435,703 filed Nov. 8, 1999 entitled MULTIPLE PRECISION DOSE PRESERVATIVE FREE MEDICATION DELIVERY SYSTEM provides a nozzle and medicament reservoir combination that enables multiple dose delivery of a preservative-free product with accurate dose dispensing over extended periods of time.
As described in this reference a spring in an actuator is compressed by a button disposed at a rear of a housing. This compression causes a fluid reservoir the actuator together. The compressed condition is held by a latching mechanism and upon release of the latch, by a trigger, the two parts are rapidly accelerated apart from each other in an axial direction and the actuator or pump, produces a dose that is sprayed out of a nozzle.
The present invention includes apparatus for instilling a medicament into an eye, an apparatus for operating an eye drop dispenser.
The apparatus generally includes a housing having a front and a rear with a longitudinal axis therebetween with a reservoir disposed in the housing for containing a medicament. A nozzle is provided and disposed approximate the housing front for instilling a dose of the medicament into an eye and a spring driven actuator is provided for metering doses of medicament from the reservoir to the nozzle and forcing each metered dose through the nozzle upon forward axial displacement of the actuator by the spring along the longitudinal axis.
More particularly, the apparatus includes a drawbar disposed for longitudinal movement within the housing and along the reservoir. The drawbar includes a front end for engaging the actuator in order to compress the spring upon rearward longitudinal movement of the drawbar and a connecting rod having a first end, pivotally attached of a second end of the drawing bar, is provided for causing rearward longitudinal movement of the drawbar upon pivoting of the connecting rod toward the drawbar. In this operation, the spring is compressed.
A push link is provided which includes a first end, pivotally attached to a second end of a connecting rod, for pivoting the connecting rod toward the draw bar and a track guides the push link toward the drawbar.
An actuator lever, pivotally attached to a second end of the push link, enables manual urging of the push link along the track.
Importantly, the push link has sufficient length for enabling the lever to urge the push link first end past an end of the track to cause release of the compressed spring, concomitant longitudinal movement of the drawbar and actuation of the actuator without release of the lever.
Thus, the apparatus may be operated by a simple depression of the actuator lever without having to release the lever or to separately activate the activator by either a spaced apart trigger or a second depression of the lever. Hence, a single depression of the actuator lever provides for xe2x80x9cone shotxe2x80x9d actuation for metering a single dose of medicament into an eye.
More particularly, the track may be disposed in a generally perpendicular relationship to the drawbar and the lever may have a first end pivotally attached to the push link second end and the second end pivotally attached to the housing. To accommodate for this relationship, the lever may have an L shape.
In a disposable embodiment of the present invention a clamp is provided for fixing the dispenser reservoir within the housing. In another embodiment of the present invention, a sleeve is provided for holding the dispenser and the reservoir within the housing. In this embodiment, the sleeve receives the dispenser in a replaceable manner and the drawbar first end is pivotally attached to the drawbar for enabling replacement of the dispenser in the sleeve.
Preferably, the present invention includes a pair of drawbars, a pair of connecting rods, a pair of push links, a pair of tracks and a pair of actuation lever disposed on opposite sides of the dispenser. In this instance, an actuator bar interconnects the lever first ends and is disposed on a side of a housing for enabling simultaneous depression of the actuation levers.